1. Field of the Invention
The present invention generally relates to an apparatus and method for facilitating deployment of a tubular string (i.e., tubing) in a casing string or wellbore. More specifically, the present invention provides a rupture assembly for use at the bottom of a tubing string that in conjunction with a sealing assembly higher up in the tubing string, creates an airlock or buoyancy chamber in the tubing to allow a float environment during deployment of the tubing where in the rupture and sealing assemblies are designed to rupture from applied hydraulic pressure in a way to make for easy removal of the pieces once the tubing is set at the desired depth in the casing string or wellbore.
2. Description of the Related Art Including Information Disclosed under 37 CFR 1.97 and 1.98
For conventional wells, such as in steam-assisted gravity drainage (SADG) wells, it is often difficult to run or deploy the tubing, which tends to be large OD (outer diameter) tubing, to great depths due to the friction created between the tubing string and the casing. Such friction results in a substantial amount of drag on the tubing. This is particularly true in horizontal and/or deviated wells. In some cases, the drag on the tubing can exceed the available weight in the vertical section of the wellbore. If there is insufficient weight in the vertical section of the wellbore, it may be difficult or impossible to overcome drag on the tubing in the wellbore, such that the weight cannot overcome the friction forces and stops the progress of the tubing string downhole, or in some scenarios where the friction force can be overcome, the outside of the tubing or inside of the casing may be damaged as the tubing is forced downhole.
Various attempts have been made to overcome the problem of drag and achieve greater well depths of the tubing in both vertical and horizontal sections of the well. For example, techniques to alter wellbore geometry are available; however these techniques are time-consuming and expensive. Also, techniques to lighten or “float” the tubing have been attempted to extend the depth of well. For example, there exists techniques in which the ends of a tubing string portion are plugged and the plugged portion is filled with a low density, miscible fluid to provide a buoyant force. After the plugged portion is placed in the wellbore, the plugs must then be drilled out so that the miscible fluid can be forced out into the wellbore. That extra step of drilling out the plugs increases completion time. Other flotation devices require a packer to seal the tubing above the air chamber. Another example of creating an air chamber is disclosed in U.S. Published Application No. 2014/0216756, entitled Casing Float Tool, the contents of which are hereby incorporated by reference in their entirety.
Therefore, a need exists for an apparatus and method that facilitates deployment of a tubing string in a casing string by creating and maintaining an airlock or buoyancy chamber, which is easy and relatively inexpensive to install on the tubing string. Furthermore, it would be desirable if the apparatus was easily removed from the wellbore and/or that the removal results in full tubing ID so that various downhole operations could be readily performed and maximum flow rate following removal or opening of the buoyant chamber.